Ninety-seven years ago, nuclear Armageddon decimated planet Earth, destroying civilization. The only survivors were the 400 inhabitants of 12 international space stations that were in orbit at the time. Three generations have been born in space, the survivors now number 4,000, and resources are running out on their dying “Ark” – the 12 stations now linked together and repurposed to keep the survivors alive. Draconian measures including capital punishment and population control are the order of the day, as the leaders of the Ark take ruthless steps to ensure their future, including secretly exiling a group of 100 juvenile prisoners to the Earth’s surface to test whether it’s habitable. For the first time in nearly a century, humans have returned to planet Earth. Among the 100 exiles are Clarke, the bright teenage daughter of the Ark’s chief medical officer; Wells, son of the Ark’s Chancellor; the daredevil Finn; and the brother/sister duo Bellamy and Octavia, whose illegal sibling status has always led them to flaunt the rules. Technologically blind to what’s happening on the planet below them, the Ark’s leaders – Clarke’s widowed mother, Abby; the Chancellor, Jaha; and his shadowy second in command, Kane – are faced with difficult decisions about life, death and the continued existence of the human race. For the 100 young people on Earth, however, the alien planet they’ve never known is a mysterious realm that can be magical one moment and lethal the next. With the survival of the human race entirely in their hands, THE 100 must find a way to transcend their differences, unite and forge a new path on a wildly changed Earth that’s primitive, intense and teeming with the unknown.

Season 1 , Episode 1 - “Pilot”
Ninety-seven years ago, nuclear Armageddon decimated planet Earth, destroying civilization. The only survivors were the 400 inhabitants of 12 international space stations that were in orbit at the time. Three generations have been born in space, the survivors now number 4,000, and resources are running out on their dying “Ark.” Among the 100 young exiles are Clarke, the bright teenage daughter of the Ark’s chief medical officer; the daredevil Finn; the brother/sister duo of Bellamy and Octavia, whose illegal sibling status has always led them to flaunt the rules, the lighthearted Jasper and the resourceful Monty. Technologically blind to what’s happening on the planet below them, the Ark’s leaders – Clarke’s widowed mother, Abby; Chancellor Jaha; and his shadowy second in command, Kane – are faced with difficult decisions about life, death and the continued existence of the human race.

Season 1 , Episode 2 - “Earth Skills”
Clarke leads a rescue team to retrieve Jasper while the council votes on "culling" excess citizens from the space station. Abby comes up with a plan to learn the true fate of the 100, and enlists Raven to help her.

Season 1 , Episode 5 - “Twilight’s Last Gleaming”
Clarke’s newfound romance with Finn is threatened. Octavia suffers a blow to the head and wakes up to find a Grounder watching her. On the Ark, Abby exposes Kane’s plan to reduce the population of the Ark. Jaha and Abby notice a signal and realize at least some of the 100 must still be alive on Earth.

Season 1 , Episode 11 - “The Calm”
With a low food supply at camp, Clarke and Finn lead a group out to hunt for food and wind up in a compromising position. With Finn's life in danger, Clarke makes a game-changing decision. Meanwhile, Raven makes Bellamy an offer he can't refuse. On the Ark - Kane risks his life and is reunited with Chancellor Jaha and Abby.

Season 1 , Episode 12 - “We Are Grounders - Part 1”
Clarke and Finn escape one dangerous situation only to find themselves faced with a new enemy. Bellamy makes a heroic move to save Jasper. Raven faces a new danger, and Murphy finally gets his revenge. Meanwhile, those remaining on the Ark are coming to terms with the inevitable.

Season 1 , Episode 13 - “We Are Grounders - Part 2”
Clarke pleads with Bellamy to do the right thing as conflict on the ground comes to a head. Bellamy forces Octavia to make a difficult decision. Raven and Jasper work against time and Finn makes a bold move. Meanwhile, the situation on the Ark comes to a stunning conclusion.